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Art. XVII . — Description of a Hydro-Pneumatic Lamp. By 
Andrew Fyfe, M. D. F. R. S. E. Lecturer on Chemistry, 
Edinburgh. 
The discovery of Professor Dbbereiner, of the ignition of 
spongy platinum by hydrogen, naturally led to its application as 
a means of affording an instantaneous light-giving machine. 
Different instruments have accordingly been constructed for this 
purpose ; the first of which was that some time ago recommend- 
ed by Gay Lussac, for keeping a store of hydrogen, and im- 
proved by Mr Garden of London. It is, however, expen- 
sive, and not easily managed by those not accustomed to the 
use of chemical apparatus. 
Another has been invented by Mr Adie, which, though 
much less complicated, may, by many, be considered also as too 
expensive. The one I have employed for some time past, com- 
bines the advantages of simplicity, cheapness, and facility of ma- 
nagement, while it answers the purpose equally well with those 
above mentioned. 
It consists merely of a bent glass-tube ABC (Plate XI.), 
the internal diameter of which is nearly an inch. It is open at 
both ends ; fixed into a wooden stand B. The short limb C, 
is 5, and the long one A, 8 inches in length. To the mouth C 
there is ground a glass- tube, to which is fixed a stop-cock D. 
At E there is a brass ring fitted closely to the tube, and from 
which there proceeds a piece of brass, to which the spongy pla- 
tinum F is fixed by very fine wire. 
As the platinum loses its power of ignition by exposure to 
air, or rather requires a large supply of hydrogen, I have it co- 
vered with a cap, represented by K, and which is ground accu- 
rately on the cylinder L. When the lamp is required for use, 
a piece of zinc is put into the short limb as at G, and which is 
prevented from coming nearer than about an inch from the 
bending, by a tube of glass as at H. Diluted sulphuric acid is 
then poured in, so as to fill, as far up as I, after which the stop- 
per and stop-cock are introduced. By the action of the acid on 
the metal, hydrogen is generated, which fills the short limb, and 
raises the fluid in the opposite one : and the production of gas 
